(1) Field of the Invention
This invention relates to fresh produce and more particularly to the transportation of said produce.
(2) Description of the Prior Art
Before this invention, fresh harvested produce such as radishes had been loaded into trailers and chilled by a water flood. The water was flooded into the trailer by inserting water pipes into the open doors of the trailer and leaving the doors open for the water to drain from the trailer after it had flushed the product. After the product was chilled, the normal atmosphere was purged from the trailer and from the produce by flooding the area with nitrogen gas as produced by liquid nitrogen. Thereafter the trailer was closed as tightly as possible and sent to its destination. During this time, conventional refrigeration units were provided to keep the contents as near as possible to 32.degree. Fahrenheit.
Before filing this application, a search was made in the United States Patent and Trademark Office and the following patents were found:
______________________________________ JOHNSON ET AL 2,479,840 ELLIS 3,153,917 SNELLING 3,385,073 LICHTENBERGER ET AL 3,421,336 MAURER 3,525,235 ______________________________________
JOHNSON ET AL discloses cooling a refrigerated car by the expanding of liquid air. As described in column 5, line 11 of that patent, the liquid air might contain more oxygen than the atmosphere itself, or it might contain less oxygen.
ELLIS discloses discharging liquid nitrogen below floorboards within a compartment. Fresh food within the compartment would be chilled, but not frozen.
SNELLING discloses a refrigeration system for shipping perishable commodities having a heat exchanger (evaporator) at the top of the compartment. The gaseous nitrogen is discharged to the outside of the compartment. SNELLING also discloses pulling outside air from outside of the compartment or container to within the compartment or container. Column 7, line 4 indicates that the nitrogen may be discharged within the container.
LICHTENBERGER ET AL discloses coolant conduits extending under a covered floor or channels in the floor.
It does not appear to applicant that MAURER is as significant as the above described patents.